Dataset card: point to the spatial-data-agent-db toolkit

Replace the 'SDK planned' note with the released toolkit (search, gene search, downloads, MCP). No data files changed.

README.md

@@ -35,4 +35,14 @@ Source index SHA256: `909c4ec50e71c636eadc7bf01a9479fef1b4fd480ac348dfea6b785e56
 
 ## Access and reuse
 
-Browse the public catalog, request access to the [full sample data](https://huggingface.co/datasets/Biogod/SpatialDataAgent-DB), then retrieve H5AD, available TIFF images and JSON metadata. AnnData/Scanpy can read downloaded expression files. Streaming training shards and the Python SDK are planned follow-up outputs.
+Browse the public catalog, request access to the [full sample data](https://huggingface.co/datasets/Biogod/SpatialDataAgent-DB), then retrieve H5AD, available TIFF images and JSON metadata. AnnData/Scanpy can read downloaded expression files.
+
+The [spatial-data-agent-db toolkit](https://github.com/Biogod2020/spatial-data-agent-db) is a Python package, CLI and
+MCP server for AI agents.
+
+- Without an account, it searches this catalog by keywords and filters. It also searches by measured gene
+  through `catalog/feature-index.sqlite.gz`, the features of every sample's expression file
+  (`catalog/feature-index-provenance.json`).
+- With approved access, it plans, downloads, verifies and reads samples.
+
+Streaming training shards remain a planned follow-up output.